The Mercedes-Benz C280 brake light utilizes P21/5W and P21W bulb sizes depending on the specific version of the vehicle. Data for the bulb sizes covers the range from 1994 to 2007.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz C280 brake light specifications reference two distinct bulb types across the model's production years: P21/5W and P21W. Both follow the ECE standard used in European and worldwide automotive lighting.
The P21W is the most frequently listed bulb in the C280 brake light specifications, covering the 1994-2000 model years for the main brake lights. It is a single-filament signalling bulb rated at 12V and 21W, fitted with a BA15s bayonet base.
The 2006-2007 model years use the P21/5W bulb for the main brake lights. This is a dual-filament signalling bulb rated at 12V with a 21W primary filament and a 5W secondary filament, and it uses a BAY15d bayonet base.
The BA15s base of the P21W and the BAY15d base of the P21/5W are not interchangeable. The BAY15d base features two offset pins to prevent incorrect installation, while the BA15s base has a single contact pin, making the two physically incompatible despite their similar appearance.
The dual-filament design of the P21/5W allows a single bulb to serve both a running light function and a brighter brake light function simultaneously, which differs from the single-filament P21W used in earlier model years.
The Center High Mount Stop Light on the C280 uses the H21W bulb for the 1996-2000 model years. This is a single-filament signalling bulb rated at 12V and 21W, but it uses a BAY9s base, which is physically distinct from the bases used by both the P21W and P21/5W.
The BAY9s base of the H21W is not compatible with the BA15s or BAY15d bases found on the P21W and P21/5W respectively, meaning the Center High Mount Stop Light requires a separate and specific bulb type from the main brake lights.
All three bulb types listed in the C280 specifications, P21/5W, P21W, and H21W, operate on a 12V electrical system and share a 21W primary wattage rating, though their base types and filament configurations differ.